Control valves and valve actuators find wide application in a number of industries, such as power generation of all types, petroleum and petrochemicals, textiles, paper, and food processing. Control valves are often used to directly and/or indirectly control temperatures, pressures, and flows within an open or closed-loop system. The operation of a control valve typically involves positioning a plug relative to a stationary seat within the valve, whereby the actuator is directly coupled to the valve plug via a stem that is used to move the valve plug to the desired control position. The action of the valve stem can be either linear or rotary, depending on whether the valve is a liner or rotary valve.
It should be noted that frequent reference is made herein to “torque” applied by an actuator to a valve stem. However, it will be understood that, unless otherwise required by context, the term “torque” as used herein also refers to linear displacement force, according to whether the implementation of the valve actuator is rotary or linear. Similarly, valve actuation “speed” can refer to either linear or rotational speed, according to the configuration of the valve stem and actuator. Furthermore, it should be understood that the term valve “stem” as used herein is not limited to rotationally operated valve stems, but refers generically to any mechanical element of a valve that is manipulated by a valve actuator so as to adjust a degree to which the valve is open or closed.
In the simplest case, a valve actuator can be purely mechanical. However, it is often convenient to pneumatically or electrically control a valve actuator, so as to provide remote control and/or monitoring. This can allow the valve to be located in a remote, dangerous, flammable, and/or toxic environment, and/or in a location that is inconvenient or difficult to reach.
Due to their potential implementation in remote and/or harsh environments, as well as overall long-term reliability considerations, many remotely controlled actuators include only a few, well-sealed penetrations of their housing, typically for main power input, remote data communication, and mechanical connection to the valve.
The remote control of a valve actuator can be “manual,” for example by adjustment of a potentiometer. In other cases the function of the valve actuator is includes onboard control electronics that enable the actuator to perform more complex tasks without requiring immediate, local, human intervention, such as process control, regulation, implementation of speed/torque profiles, and/or emergency shut-off. Typically, the control electronics in such actuators are able to communicate with and be controlled by remote laptops and/or other such devices.
Electronically controlled actuators typically require application settings, speed/torque profiles, and/or other data to be entered into their control electronics prior to operation, so that the actuator can function correctly. This data can include an open position, a close position, a torque trip limit (to protect against applying a torque to the valve that exceeds its operational limitations), an operating speed or speed profile, and/or option settings for communication and for input and output of data, to name a few.
Typically, an electronically controlled actuator is powered by an external power source that is provided to the actuator at the installation site, such as a 3 phase AC power line, a single phase AC power line, or a 24-250 V DC power system. Once the control electronics are powered up and energized, the actuator is ready for configuration information to be entered and/or stored data to be retrieved via a local control station or an external device such as a laptop computer.
In addition to configuration information, status and alarm information can be retrieved from the actuator control electronics, for example when troubleshooting a system failure. Once the actuator is powered, such status and alarm information can be displayed on a local control display, if available, or remotely captured on a device such as a laptop computer.
Power must be supplied to the control electronics before any of these data-exchange functions can occur. However, there can be circumstances where data entry into, or data retrieval from, an electronic actuator is desired, but it is not convenient or not possible to connect a power source to the actuator. Some examples of situations where this can occur are:
During preparation of a newly purchased actuator for delivery to a user.
During a maintenance cycle of the actuator.
If user-supplied power fails at the end-user installation.
In these situations, where local power is not available to power the actuator, it can be difficult or impossible to exchange data with the control electronics of an electric actuator.
What is needed, therefore, is an apparatus and method for exchanging data with control electronics of an electronic valve actuator when it is inconvenient or impossible to connect the actuator to a conventional power source.